This invention relates to fluid pressurizing devices for balloon catheters or the like, and more particularly relates to an improved device for actuating a screw plunger and monitoring the resulting fluid pressurization.
Fluid pressurization devices adapted for selectively applying and relieving a measured pressure on a closed volume of fluid have been developed for use in inflation and deflation of a balloon catheter used in angioplasty balloon procedures interiorly of blood vessels, or other types of balloon catheterization procedures. For example, U.S. Pat. No. 4,838,864 discloses a syringe device which inflates and deflates a catheterized balloon. The device uses a manually-operated screw plunger to achieve or maintain specific balloon pressure, and the pressure is monitored using an associated pressure gauge. Improved syringing and pressurization control is also described in U.S. Pat. Nos. 5,168,757 and 5,713,242, both of which are incorporated herein in their entirety by reference. The '757 and '242 patents disclose quick release mechanisms which enable rapid advancement of a threaded screw plunger and alternatively allow threaded engagement with the screw plunger to achieve precise control during final pressurization of a balloon catheter.
A cross-sectional view of the device which is disclosed in U.S. Pat. No. 5,713,242 is shown generally in FIG. 1 (FIG. 1 corresponds to FIG. 2 of the '242 patent). As shown, the device 10 provides that a piston 12 is engaged with a plunger 14 inside a fluid displacement chamber 16 provided in a housing 18. The design of the device 10 (see specifically walls 20 and 22 of the housing 18) is such that the piston 12 must be front-loaded into the fluid displacement chamber 16. More specifically, the piston 12 is slid into the front 24 of the fluid displacement chamber 16, from left-to-right in FIG. 1, and then a fitting 26 and a clamping cover 28 is engaged and sealed with the end of the housing 18 to close off the end 24 of the fluid displacement chamber 16. It is important to provide that the chamber 16 is sealed because the chamber 16 becomes pressurized when the device 10 is in use. The fitting 26 carries a gauge 30 which is configured to monitor the pressure of the chamber 16 while the device 10 is used. Because the clamping cover 28 and fitting 26 are parts which are distinct from the housing 18, the parts must be manually handled, which complicates the assembly process and consumes labor. Additionally, these extra parts, being located at the distal end (i.e. the end where the clamping cover 28 and fitting 26 are located) of the device 10, may obstruct the view of a physician who is attempting to purge the device by getting all the air bubbles out of the chamber 16.
The present invention is an improvement on this prior art design as it involves a construction which permits the unit to be assembled entirely from the rear. Thus, the main housing, including the forward portion that receives and supports the pressure gauge can be fabricated as a single, integral component. Additionally, the design provides that many of the parts are universal such that they are compatible with devices of different sizes.